Stewart is convinced Gudelj can develop into one of the best midfielders in Europe.

"He was in the express sights of clubs like Hamburg SV, Newcastle United and Fiorentina. However, AZ fitted better in his picture. That says a lot about him," said Stewart on the website of the Alkmaar club.

"Nemanja has the potential physically and skills-wise to reach the European summit.

"He is a player with a great attitude, great endurance and a lot of qualities."